Complex event detection over data streams has become ubiquitous through the widespread use of sensors, wireless connectivity and the wide variety of end-user mobile devices. Typically, such event detection is carried out by a data stream management server executing continuous queries, previously submitted by the users. In this paper, we consider the situation where the end-users submit queries from hand-held devices and the results of the continuous queries, which are in the form of individual data streams, are disseminated to the users over a shared broadcast medium. Specifically, we propose three power-aware query operator placement algorithms that determine which part of a continuous query plan is executed at the data stream management server and which part is executed at the users' wireless device. The algorithms' effectiveness with respect to energy consumption is evaluated using simulation.